The present invention relates to a process and to a device for producing foam casings from CFC-free polyurethane foams made with a blowing agent which in combination with atmospheric oxygen has the potential to form an explosive mixture such as pentane, butane or hexane.
In the production of foam casings, particularly refrigerator casings, blowing agent which is released during foaming inside the casing can form an explosive mixture with the atmospheric oxygen present in the casing. There is a risk that the casing (in the case of refrigerator casings, the so-called "inner liner") can charge with static which can lead to a brush discharge and thus to explosion.
Attempts have been made to make the inner liner electrically conductive by means of a coating to prevent electrostatic charges by grounding. Another possible method for preventing static would be to purge the entire space in which the foam is to be formed with ionized air to break down electrostatic charges. However, each of these methods is quite complicated and expensive.